Currently, misprision of felony is codified in 18 U.S. Code § 4 – Misprision Of Felony. Originally made a law in 1789, the current version in the code listed was created in 1909. Whereas the original common law version from England only required knowledge of the law for you to be required to report it, the United States federal law version requires there be some form of concealment. It reads as follows:
Whoever, having knowledge of the actual commission of a felony cognizable by a court of the United States, conceals and does not as soon as possible make known the same to some judge or other person in civil or military authority under the United States, shall be fined under this title or imprisoned not more than three years, or both.
I thought it was a crime to cover up a felony.
https://felonies.org/is-it-a-crime-to-not-report-a-felony/